The present invention relates to a device for adjustment of the ignition time in internal combustion engines as a function of the vacuum in the intake line which has a flow regulator such as, for example, a throttle valve and further including a vacuum device comprising a distributor advance chamber and a distributor retarding chamber.
In current automobile ignition systems, it is conventional to delay ignition time in order to reduce harmful exhaust substances, such as hydrocarbons and NO.sub.x. However, a delay in ignition time results in both lower thermal efficiency and lower engine productivity, with a consequent impairment of engine performance. This impairment of engine performance is particularly evident with cold ambient conditions and in engine warm-up.
It is already known, German Patent No. 596,918, that better combustion with a cold engine can be obtained by advancing the ignition. Ignition advance toward normal ignition can be adjusted as a function of a predetermined engine temperature, but an internal combustion engine provided with such an ignition timing arrangement cannot be driven at maximum power due to the knocking combustion region that is encountered early.
In a warmed-up internal combustion engine, the knock threshold depends upon ambient conditions, particularly the temperature of the air intake and air pressure. The margin of safety between full-load ignition and the knock threshold must be adapted to the most unfavorable ambient conditions that can be expected to occur as a whole in the operation of the internal combustion engine. Thus, in the average set of ambient conditions, the maximally useable output of the internal combustion engine is less than desired.